The Hollywood thriller The Day After Tomorrow has introduced movie audiences around the world to the idea of abrupt climate change. In the film, a sudden new ice age caused by global warming leads to massive destruction. Much of the film is set in New York City, which is hit by a tidal wave, and then becomes encased in a thick layer of ice.

When the film opened, a group of climate scientists and political leaders, including former Vice President Al Gore, held a public forum in New York to warn about the potential consequences of abrupt climate change. They agreed that these changes would not happen anytime soon or as fast as the film suggests, but Princeton University's Dr. Michael Oppenheimer said that even on a slower timetable, the effects of abrupt climate change could be devastating.

"I live in the middle of Greenwich Village, in the middle of the lower part of the island. If the Greenland or West Antarctic Ice sheet were to crumble completely, which is a plausible outcome for subsequent centuries - if that happens, my descendants may well be the proud owners of beach-front property in the center of Manhattan."

In some parts of the federal government, concern is growing over the possibility of sudden destructive changes to the world's climate. Peter Schwartz recently wrote a report for the Pentagon warning that abrupt climate change could lead to regional emergencies.

"We will see a number of refugee crises and humanitarian crises around the world where the U.S. might be called in to intervene and help manage the crisis."

Schwartz's Pentagon report predicts rising international tensions over climate-related shortages of food, water and energy.